/*
 * Copyright (c) 2011-2012 Alexander Dubu
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * o  Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * o  Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * o  Neither the name Axil nor the names of its contributors may be used to
 *    endorse or promote products derived from this software without specific
 *    prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

package axil.definition;

import axil.api.extend.SourceAdapter;
import axil.api.extend.SourceAdapter.Kind;
import axil.engine.AxilEngine;
import axil.etc.Compressed;
import axil.etc.Identity;
import axil.framework.localization.Namespace;
import axil.framework.validation.Validated;
import axil.framework.validation.ValidationContext;
import axil.framework.xml.InputXML;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Unmarshaller;
import java.io.Reader;

import static axil.framework.Functions.*;


/**
 * The generic base class for various XML-based definitions.
 */
abstract class Definition implements Compressed, Validated, Identity {
	public static final Namespace ns = AxilEngine.ns.ns("definition");

	private String name;
	private String title;
	private String description;


	protected Definition(InputXML xml) {
		this.name = xml.content("name");
		this.title = xml.content("title");
		description = xml.content("description");
	}


	/**
	 * Return a string by which this object's value can be identified. The
	 * string returned cannot be null, but may be empty.
	 */
	public String identity() {
		return require(name);
	}


	public String name() 		{
		return name;
	}
	public String title() 		{
		return title;
	}
	public String description() {
		return description;
	}


	protected static JAXBContext context(Class... classes) {
		try {
			return JAXBContext.newInstance(classes);
		} catch (JAXBException e) {
			throw new RuntimeException(e);
		}
	}



	protected static <T> T read(Class<T> type, Kind kind, JAXBContext context,
	                            String module, String name) {
		for (SourceAdapter adapter : AxilEngine.instance().sources()) {
			Reader r = adapter.definition(module, kind, name);
			if (r != null) {
				try {
					Unmarshaller u = context.createUnmarshaller();
					return (T)u.unmarshal(r);
				} catch (JAXBException e) {
					throw abort(e, "Problem deserializing function definition.",
					            nv("function", name));
				} finally {
					close(r);
				}
			}
		}
		throw abort("The definition cannot be found.",
		            nv("function", name),
		            nv("module", module));
	}


	/**
	 * Validate this object in the given context. Any problems detected with the
	 * correctness or completeness of this object are placed into the context.
	 * This method descends into its owned members, validating them as well.
	 */
	public void validate(ValidationContext context) {
		context.check("name", identifier(name), msg(ns, "invalid-identifier"));
		context.required("description", description);
		context.required("title", title);
	}


	/**
	 * Compress this object, reducing its memory footprint as much as possible.
	 * A compressed object is still fully functional for script evaluation but
	 * may no longer possess complete metadata.
	 */
	public void compress() {
		title = null;
		description = null;
	}
}
